This application relates to high power compression assembled semiconductor packages, and more particularly to a compression assembled semiconductor package that houses a high power semiconductor switching die.
Compression assembled packages for housing high power semiconductor elements are well known. These packages generally resemble a hockey puck and include a power semiconductor die, which may be a thyristor, having a control electrode and a major electrode on a major surface thereof, and another major electrode on its opposing major surface. Typically, in these packages, two relatively large pole pieces are pressed by outside supports in surface-to-surface electrical contact with the major electrodes of the semiconductor die.
Typically, an annular insulation ring comprising a dielectric ceramic is disposed around the semiconductor die. The pole pieces are then directly connected to respective ends of the annular insulation ring by, for example, brazing and retain the semiconductor die within the annular insulation ring due to the pressure from the outside supports. Also, typically such well known compression assembled packages include a structure that allows a control signal to be carried from an external control circuit to the control electrode of the semiconductor die, whereby the semiconductor die may be switched ON to allow conduction between the poles of the package and OFF to prevent the conduction. Hence, compression assembled semiconductor packages find much use as switching devices within an electronic circuit.
A compression assembled semiconductor package according to the present invention includes a semiconductor device which is in surface-to-surface electrical contact and secured between respective surfaces of a top pole piece and a bottom pole piece. An annular insulation ring which is made from a molded plastic is disposed around the semiconductor die. The bottom pole piece includes a radially extending flange which penetrates the interior wall of the annular insulation ring and is embedded therein. An annular flange also penetrates and is embedded in the annular insulation ring at one end thereof. The top pole piece includes a rib which connects to the annular flange through a circular connector, thereby connecting the top pole piece to the package. As a result, the semiconductor die is held in place within the annular insulation ring by being compressed between the two pole pieces.
In one embodiment, the compression assembled semiconductor package of the present invention includes a control lead which extends from its interior to its exterior. The control lead is preferably a copper tab which is electronically connected to the control terminal of the semiconductor die by a bond wire. Together, the bond wire and the control lead form a control signal carrier for the compression assembled semiconductor package which will be connected to a control circuit.
In another embodiment of the present invention, a resilient L-shaped spring tab is welded at one end to the control lead that extends from the interior of the annular insulation ring to its exterior. The other end of the L-shaped spring tab is urged to form an intimate electrical contact with the control electrode of the semiconductor die due to the biasing force of the resilient body of the L-shaped spring tab.
In yet another embodiment, the control signals are transmitted to the control electrode of the semiconductor die by a spring tab. The spring tab in this embodiment is a unitary body that includes one portion which extends through the body of the annular insulation ring to the exterior thereof. The portion of the spring extending outside of the annular insulation ring acts as a control lead. The spring tab of this embodiment is also resilient and includes a head portion which is kept in intimate electrical contact with the control electrode of the semiconductor die due to the biasing force exerted by the springy, resilient body of the spring tab.
A compression assembled semiconductor package according to the present can be assembled easily, using less expensive parts with no sacrifices in electrical or thermal performance.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.